Hmrc Basic tools not able to update

If this is the software in the question and refer to link below

https://www.gov.uk/basic-paye-tools

Last updated 7 June 2019 which was before macOS 13 Ventura was released to the Public as a Stable Version and not Beta Version

Would seriously suggest communicating with the Developer of this software for guidance

The wheels of progress especially when dealing with Governments are slow.

When they decide something is " Right and Works " on macOS Ventura - good luck with that I am sorry to say 🇨🇦